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Effect of processing at up to 1400 K under Ar hydrostatic pressure (HP) equal to 1.1 GPa for oxygen-containing Czochralski grown silicon (Cz-Si) irradiated with neutrons (energy E = 5 MeV , dose D = 1 × 10 17 cm - 2 ) or γ -rays ( E = 1.2 MeV , D = 1000 Mrad ) on oxygen clustering and precipitation has been investigated by electrical, X-ray, infrared absorption, and photoluminescence methods. Depending on irradiation conditions, processing of irradiated Cz-Si, especially under HP, results in creation of oxygen-containing defects. Such processing of irradiated Cz-Si is helpful for revealing its irradiation-related history.

Transients and relevant response times of a-Si : H p-i-n photodetector under various illuminations (in the visible range) and bias voltage conditions were studied. The model/method for possible color detection using on and off transient response times is proposed. Depending on illumination and bias pulse types, one or two processes are found to be involved in the conduction mechanism, including transition and trapping of both charge carrier types. Characteristic photocurrent transients and response times under modulated monochromatic and chromatic visible light illumination enable color recognition. The peculiar behavior of the blue light transients has been also plausibly explained by means of the proposed model

A new technique of color detection based on time-resolved charge collection during transient response measurement using a hydrogenated amorphous silicon detector has been proposed and experimantally demonstrated. The method based on the material intrinsic wavelength-filtering properties is implemented in color sensing by transient response of a detector to a combination of basic colors light and voltage pulse. Resulting transient responses under different illumination and bias voltage conditions confirm considerable accuracy of proposed method. In particular, the best agreement of measured and calculated transient response curves has been obtained by using the spectral response of all three primary colors in calculations. It was observed that the presence of blue light drastically reduces the transient response to a chromatic light illumination. Finally, a voltage pulse influence to the basic colors transient response was found.

The study of irradiation effect of γ rays for 60 Co source on n -type carbon-free and carbon-rich Czochralski silicon single crystals is presented, based on deep level transient spectroscopy technique. It is shown that generation of vacancy-related defects is significantly enhanced in carbon-rich silicon in respect to carbon-free samples. Divacancy and multivacancy-related defects were particularly enhanced. The observed behavior is discussed and related to the carbon presence in the bulk. Carbon trapping of self-interstitials significantly enhanced vacancy concentration that further caused observed behavior.

A detailed analysis of the EPR line-shape was performed on amorphous silicon (a-Si) samples obtained by Kr + ion implantation. It is shown that the line has predominantly Lorentzian character, however, a small Gaussian component is present as well. We monitored line-shape behavior during the relaxation and subsequent derelaxation process. A strong, fourfold increase in Gaussian component has been observed upon structural relaxation, suggesting spin homogenization throughout the bulk. Subsequent ion implantation derelaxation caused gradual return of the Lorentzian character, i.e. cluster structure of the amorphous phase.

In this paper we show that the orthorhombic phase of ${\mathrm{FeSi}}_{2}$ (stable at room temperature) displays a sizable anisotropy in the infrared spectra, with minor effects in the Raman data too. This fact is not trivial at all, since the crystal structure corresponds to a moderate distortion of the fluorite symmetry. Our analysis is carried out on small single crystals grown by flux transport, through polarization-resolved far-infrared reflectivity and Raman measurements. Their interpretation has been obtained by means of the simulated spectra with tight-binding molecular dynamics.

The various polycrystalline silicon materials (cast ingots, ribbons) which are commercially available for the solar cells manufacturing differ very much among themselves due to the different growth processes. The resulting microstructure and impurity content will influence differently the material characteristics during thermal treatments inherent to the device manufacturing. As the gettering efficiency depends on the kind of polycrystalline material, the variations observed in the optimal gettering conditions or passivation will be discussed. In this paper, we compare the performances of various types of polycrystalline silicon upon classical and rapid thermal-process-induced co-diffusion of phosphorus and aluminium. We show that a large bulk minority carrier diffusion length enhancement occurs in the case of co-diffusion when compared to the separate diffusion of phosphorus and aluminium.

A detailed analysis of the electon paramagnetic resonance line shape was performed on amorphous Si samples obtained by Kr+ ion implantation. The Lorentzian character and behavior upon annealing was explained via a strong exchange interaction, leading to a cluster model for the spin density distribution. The saturation measurements are shown to be a convenient method to study structural changes caused by thermal annealing. The spin density distribution (as described with the cluster model) imposes a clear difference between amorphous Si material obtained by ion implantation and one obtained by evaporation and/or chemical vapor deposition.

Several techniques were used to study a surface layer structure of edge-defined film-fed grown polycrystalline silicon samples grown in CO gas deliberately added to the purging atmosphere. Although infrared analysis reveals the presence of cubic SiC structures, other techniques, such as spectroscopic ellipsometry and Raman spectroscopy, do not detect its presence. It is concluded that a layer with specific structure, formed in the course of ribbon growth, consists of indiffused oxygen formed upon reaction of CO gas with molten Si. Indiffused oxygen, in turn, induces coaggregation of carbon and silicon selfinterstitials that probably play the role of SiC nucleation centres, but do not have the thermal stability of SiC.

In this paper the transient photo-dark current ratios (PDCR) of p-i-n a Si:H amorphous silicon photodiode on voltage pulse at constant light and on a simultaneous light and voltage pulses were measured and compared. The results show opposite PDCR behavior of monochrome and chromatic transients in these two cases. From the measured dark current and the photocurrent, which are both proportional to the instantaneous charge change, the charge was calculated using the FFT method. The obtained results show that the depletition charge increments are much smaller than the stored ones.

Presented in this paper is a study of the visible light detection by the hydrogenated amorphous silicon p-i-n sensor under low reverse bias, where linear increase of photocurrent under different illumination condition is observed. The method based on the material intrinsic wavelength-filtering properties is implemented in color sensing. The response times after switching on and off monochromatic and chromatic illumination at constant reverse bias voltage are analyzed. The results of transient response under different illumination conditions confirm the trap controlled conduction mechanism.

There is a considerable current interest in polycrystalline silicon and edge-defined film-fed growth (EFG) technique is suitable candidate for low-cost solar cell production. Recently, it has been shown that oxygen addition during the crystal growth yields a higher efficiency solar cells. We studied deep level defects associated with structural defects like dislocations and grain boundaries, and influence of oxygen addition to the bulk on the picture of deep levels in the material. We have shown that levels attributed to dislocations are directily influenced by oxygen addition. We have also found that such levels originate predominantly from grain boundaries and to lesser extent from intragrain regions.

The effect of light soaking on a-Si:H films is well known as the Staebler-Wronski effect, though its complete mechanism is not yet clear. We studied the effect of light soaking with UV, white and sub-gap light on a-Si:H films, as well as the effect of thermal annealing in the dark. It was shown that the light soaking of the films with white and sub-bandgap light in air did not affect hydrogen concentration from Si-H bonds, and at the same time, enhanced oxidation of the films is observed. It means that oxygen incorporation was due to the broken backbonds to Si-H which very likely represent weak bonds. Moreover, it was found that, subgap and white light irradiation produced oxidation, UV light did not, while UV light caused even minor Si-H bond breaking. Vacuum annealing at 100/spl deg/C in the dark, on the other hand, caused hydrogen redistribution, enhancing Si-H bond concentration and recovering broken bonds.

In this paper color detection based on transient response of n-i-p a-Si:H amorphous silicon photodiode to light and voltage pulses was described. The responses to a voltage pulse at constant light and to light pulse at constant reverse bias voltage were also measured. From the measured dark current as well as the photocurrent, which are both proportional to the instantaneous charge change, the charge was calculated using the FFT method. In the case of transient response to light and voltage pulsesthe changeable capacitance as a measure of wavelength dependent light absorption is introduced. The obtained results show the charge increments dependence on wavelength and confirm the p-i-n a-Si:H photodiode as an efficient color detector.

The influence of high-temperature thermal treatment on solar-grade polycrystalline silicon wafers was studied. It is shown that after thermal treatment at very high temperatures (about 1250 degrees C), co-precipitation of carbon and oxygen occurred, thus forming specific (C,O) complexes stable at high temperatures. The characteristic broad asymmetric peak of these complexes in an IR spectrum is similar to the respective one of SiC and therefore its formation is often attributed to pure SiC formation.

Optical spectroscopy was employed to study iron phosphate glasses of the general composition x Fe 2 O 3 (100− x )P 2 O 5 (14≤ x ≤47 mol%). Cation vibrational properties showed that iron is predominantly present as iron(II) in glasses of lower total iron content and as iron(III) in glasses of higher total iron content. In glasses containing 40 and 47 mol% Fe 2 O 3 some of iron(III) ions changed from octahedral to tetrahedral coordination. Increasing iron content increased network disorder to the point where the structural changes occur, i.e., where iron cations changed their charge or coordination.

The authors' studies have shown that during the growth of edge-defined film-fed ribbons under highly asymmetrical conditions and in an atmosphere with CO2 added, oxygen is diffused into the growing ribbon. Oxygen atoms further simulated creation of carbon and silicon self-interstitial aggregates which in turn acted as precursors for SiC phase formation. This gave rise to the characteristic peak at 797 cm-1 in the infrared absorbance spectrum. These clusters of carbon and silicon self-interstitials are not as stable as an SiC phase and therefore can be annealed during a low-temperature (650degrees) thermal treatment (10 References).

EFG silicon ribbon and two kinds of polycrystalline silicon (SILSO and HEM) obtained by casting techniques, with different concentrations of oxygen and carbon impurities have undergone thermal treatments in the temperature range from 450 to 1300°C. Infrared spectroscopy was used to monitor changes in the concentration and configuration of various defects. The carbon-to-oxygen concentration ratio and the thermal history of the investigated materials proved to be of the paramount importance in the nucleation and growth of various precipitation phenomena at higher temperatures. As distinct from single crystal silicon, grain boundaries and high dislocation densities offer an additional source of impurities which may be seen by the infrared techniques upon their activation at higher temperatures.

The authors report on infrared analysis of the SiOx-like defects segregated close to the surface of the edge-defined film-fed growth polycrystalline ribbons. These defects cause an absorption band very similar to that of the SiOx phase, but they are thermally unstable, and can be annealed by 650degreesC thermal treatment. It is concluded that they are quenched high-temperature defects formed during the film growth. Possible nucleation centers for those defects are found to be C and/or SiC aggregates close to the surface (15 References).

Various polycrystalline silicon ribbons, grown with the edge-defined film-fed growth (EFG) technique, are annealed at the temperatures from 450 to 1250degreesC. The EFG ribbon growth technique introduces high C and O concentration which results in specific annealing behavior due to defect interactions. It is shown that oxygen in-diffusion during the crystal growth produces an oxygen-rich layer close to the surface of the ribbon, containing mostly SiOx agglomerates unstable at higher temperatures. Carbon concentration that exceeds the oxygen concentration causes a formation of high-temperature [C, O] complexes which could not be found in Si material with an inverted carbon-to-oxygen concentration ratio (25 References).

The paper is a summary report of an extended investigation of the practical usability of solar energy in Yugoslavia. The main tool for calculation was TRNSYS simulation program. Meteorological data and technical parameters of typical commercial solar devices were used as input data. Solar flux data on tilted planes were obtained by means of the Liu and Jordan method. For five locations, chosen to characterize all typical climatic regions in Yugoslavia, a detailed hour by hour simulation of the performance of the typical commercial domestic hot water solar heating system (DHW) was carried out. In summer the efficiency of such a device was similar for all locations, ranging from 40 to 45 per cent. In the winter months the efficiency varied from 30 per cent in sunny coastal regions to less than 10 per cent in polluted urban areas. The same type of calculations were worked out for a combined solar-traditional space-heating system, including the investigation of the influence of some important parameters on the efficiency of the solar part of the system. Calculations show that in very polluted urban areas only low-temperature load heat exchangers are to be recommended ; in the coastal and southern parts of the country, however, high working temperature (50degreesC) is allowed which results in the average efficiency of the system of more than 25 per cent even if the worst month and even if the ordinary black-paint, double glazed collectors are used (7 References).

The thermoelectric power of four ferromagnetic FexNi80-xB20 alloys (where x varied in steps of 20) and of a nonmagnetic Pd86-Si14 alloys has been measured in the temperature interval 50–470 K. The thermoelectric powers (S) of FexNi80-xB20 alloys are negative and their temperature variation is similar to that in crystalline Fe-Ni alloys. However, their S values are for a factor of about ten smaller then those of crystalline alloys. In Fe20Ni60B20 alloy the change in S above the Curie temperature (Tc = 426 K) is observed. An interpretation of our results in terms of strong ferromagnetism is offered.

Because of the large concentration of structural defects in the SILSO, polycrystalline silicon material it is thought that a significant concentration of oxygen segregated around these defects is present in the material. As this segregated oxygen is infrared-invisible, room-temperature infrared spectroscopy of as-received samples cannot provide a realistic picture of the oxygen present in the material. After a high-temperature treatment (1250 degrees C) and dispersion and homogenisation, information about the dissolved oxygen can be obtained by infrared spectroscopy.